Method of making a disk tape commutator

ABSTRACT

A disk type commutator for a direct current motor comprising a plurality of wedge-shaped conductive members carried by an annular insulating member that provide commutator segments for the commutator. The conductive members and the insulating member have aligned apertures through which the ends of the rotor windings are inserted for connection with the conductive members at the face of the commutator. The face of the commutator is machined to provide a surface that engages the motor brushes. Both the conductive members and the rotor winding ends contact the motor brushes in operation.

States Patent 1 1 Hellmann et a1.

METHOD OF MAKING A DISK TE COMIVIUTATOR Inventors: John V. Hellmann,Anderson; Carl L. Richwine, Daleville, both of 1nd.

Assignee: General Motors Corporation,

Detroit, Mich.

Filed: Aug. 5, 1971 Appl. No.: 169,306

Related US. Application Data Division of Ser. No. 36,322, May 11, 1970,abandoned.

US. Cl. ..29/597, 310/235, 310/237 Int. Cl. ..H0lr 43/00 Field of Search..29/597, 598;

References Cited UNITED STATES PATENTS 7/1970 Arora ..310/233 7/1933 Wry..29/605UX 1 Apr. 10, 1973 3,478,421 11 1969 Preece ..29/597 2,953,6989/1960 Gianotto ..29/597 x 3,487,249 12 1969 Nicholls et 81.... .....310237 x 2,696,570 12 1954 Pandapas ..310/233 x 1,536,328 5 1925 Caruso..310/237 Primary ExaminerRichard J. Herbst Assistant ExaminerCa.rl E.Hall Attomey-C. R. Meland ABSTRACT A disk type commutator for a directcurrent motor comprising a plurality of wedge-shaped conductive memberscarried by an annular insulating member that provide commutator segmentsfor the commutator. The conductive members and the insulating memberhave aligned apertures through which the ends of the rotor windings areinserted for connection with the conductive members at the face of thecommutator. The face of the commutator is machined to provide a surfacethat engages the motor brushes. Both the conductive members and therotor winding ends contact the motor brushes in operation.

1 Claim, 5 Drawing Figures PATENTEUAFRmmm I 37,26,003:

sum 1 BF 2 INVENTORS TTORNEY METHOD OF MAKING A DISK TAPE COMMUTATORThis application is a division of application Ser. No. 36,322, filed May11, 1970, now abandoned.

This invention relates to a disk type commutator and its method ofmanufacture.

In this invention, a commutator for use in a DC motor is providedwherein a plurality of wedge-shaped conductive members molded to aninsulating member form commutator segments which are employed in thecommutation of current supplied to the rotor windings. The rotorwindings are inserted through aligned apertures in the insulating memberand the conductive members and are electrically connected with theconductive members. In this commutator, the motor brushes contact boththe rotor winding ends and the conductive members.

It is an object of the present invention to provide a disk typecommutator for a DC motor wherein apertures are provided in thecommutator which receive the ends of rotor windings and wherein the endsof the rotor windings are connected to commutator segments and form partof the commutator segments.

Another object of the present invention is to provide a method ofmanufacturing a disk type commutator for a DC motor wherein the ends ofrotor windings are inserted through openings formed in commutatorsegments and are secured to the segments, and the entire assemblyincluding the ends of the rotor winding is then machined to provide asmooth brush engaging commutating surface.

Additional objects and advantages of the present invention will beapparent in light of the following description. The accompanyingdrawings which disclose a preferred embodiment of the present inventionare incorporated in the description.

In the drawings:

FIG. 1 is a sectional view of a DC motor provided with a disk typecommutator made in accordance with the present invention.

FIG. 2 is a view partly in section taken along line 2- 2 of FIG. 1including a plan view of the disk type commutator.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 and showingthe motor brushes.

FIG. 4 is a plan view of the commutator segments incorporated in thedisk type commutator of this invention at an early stage in thefabrication process.

FIG. 5 is an end view of the. stamping shown in FIG. 4.

Referring now to the drawings and more particularly to FIG. 1, asectional view of a DC motor is shown. This DC motor 10 is comprised ofan annular frame 12, pole pieces 14, a field winding 16, and a rotor orarmature 18. The shaft of the rotor 18 is rotatably supported at itsopposite ends by bearings 20 and 22.

The rotor 18 is comprised of an armature core or body 24 formed oflaminated magnetic material that is carried by a rotor shaft 26, a disktype commutator 28 described hereinafter, and a plurality of rotorwindings 30. The commutator 28 is carried by shaft 26 and the windings30 are located within slots 31 formed in core 24. The rotor shaft 26 canbe connected to a load which is not shown and the motor can be used, forexample, as a cranking motor for cranking an internal combustion engine.Motor brushes 32 provide electrical energization of the rotor windings30 for motor operation and are slidably supported in a brush-holder 33shown in FIGS. 1 and 3 and formed of insulating material. These brushesmake contact with the conductive members 34 on the face of thecommutator 28 and they also make contact with the ends of the rotorwindings 30 in a manner detailed below.

At this time, FIGS. ll, 2, 4 and 5 should be considered. These figuresfacilitate an understanding of the structure of the commutator 28 andits method of manufacture.

In FIG. 4, two copper stampings A, B are shown wherein a plurality oftruncated wedge-shaped conductive members are formed in two connectedseries. These stampings can be formed by feeding a copper sheet into aprogressive die punch press wherein the various forming operations areperformed in successive steps as the parts pass through the die. Each ofthe wedge-shaped copper members 34 of the stampings A and B is providedwith an aperture 38 in the stamping operations. As shown in FIG. 5, thetruncated wedgeshaped conductive members 34 are provided with three tabs40 on each wedge-shaped member 34 during the stamping operations byfonning the truncated ends and the aperture material into tabs 40.

In the fabrication of a commutator, one of the stampings A or B isfolded into a substantially circular configuration with the connectingsegments 36 of FIG. 4 on the outer perimeter. The resultant copper diskis molded to a quantity of insulating material, for example, a phenoliccomposition to form the annular insulating phenolic block 42 in FIG. 1.This annular insulating member 42 is provided with apertures alignedwith the apertures 38 of the conductive members 34. These apertures inthe insulating member can be provided by known core techniques duringthe molding of they copper part to the insulating material. Thecommutator 28 of FIG. 1 shows the copper segments 34 molded to the faceof the phenolic annular member 42. As shown in FIG. 1, the insulatingmaterial extends to the surface of the conductive members 34, thusfilling the slots separating the individual commutator segments. Thetabs 40 of the copper segments 34 are molded in the annular member 42and they serve to secure the copper segments 34 to the annularinsulating member 42. A zinc core 44 is molded to the annular insulatingmember 42 during the molding operation and the resultant commutator ismounted on the rotor shaft 26 by means of an interference fit betweenthe shaft 26 and the zinc core 44 as shown in FIG. 1.

After molding the copper disk to the annular insulating member 42, theconnecting links 36, shown in FIG. 4, are machined away to provideelectrically isolated commutator segments individually supported byinsulator 42. The commutator assembly is then fitted to shaft 26 andmoved axially so that the ends of the rotor windings 30 are insertedthrough the apertures 38 in the isolated copper segments 34 and theannular insulating member 42 as shown in FIG. 2. During the insertionprocess, the copper segments 34 and the copper windings 30 aremechanically deformed as a result of interference between the coppersegments 34 and the windings 30 and an intimate copper-to-copper bond iscreated between the rotor winding conductors 30 and the copperwedge-shaped segments 34. This bond is strengthened by a solderingprocess which also affords protection against corrosion. Solder isapplied by bringing the face of the disk commutator 28 in contact withmolten solder and relying on capillary action to fill the spaces betweenthe copper segments 34 and the copper rotor windings 30.

To ensure that optimum contact is made between the brushes 32 of FIG. 1and the commutator segments 34 and the ends of the rotor windingconductors 30 which actually form a part of each commutator segment, theface of the disk commutator 28 is machined to provide a plane surfacefor commutation which includes the copper segments 34 and the ends ofthe rotor windings 30. This machining step produces a flat surfacefacilitating the commutation of current supplied the rotor windings 30.

The four motor brushes 32 of FIG. 3 ride on the machined surface of thecommutator 28. These brushes 32 are shown in FIGS. 1 and 3 supported bybrushholder 33 and are urged into contact with the copper segments 34and the ends of the rotor windings 30 by springs 48. Accordingly,current is sequentially switched in the rotor windings of the DC'motorduring periods of motor operation.

The disk type commutator disclosed hereinabove together with its methodof manufacture provides a simple, low cost commutator arrangement forinclusion in direct current dynamoelectric machines. In addition to costand simplicity, this commutator affords advantages in reliability anddurability as a result of the configuration of the commutator whereinthe rotor winding ends are captured in the commutator and included inthe commutation plane surface. Winding throw-out is virtually impossibleas a result of the captured character of the commutator-windingconnection and commutation is enhanced as a result of the brushwindingcontact which is effected by the inclusion of the rotor winding ends inthe commutation plane surface.

We claim:

1. A method of manufacturing a disk type commutator for a rotor of adynamoelectric machine, the steps comprising, providing a strip ofelectrically conductive material, cutting said material to form aplurality of wedge-shaped commutator segments connected by thinconnecting portions located along one edge of said strip, forming aconductor receiving opening in each commutator segment by cutting andforcing out two adjacent portions of each segment to form a pair ofintegral anchoring tabs extending axially from said segments, foldingsaid strip into a circular configuration with the edges of said segmentsspaced from each other and with said one edge of said strip located atthe outer periphery, molding a quantity of insulating material to theside of said folded strip having said integral anchoring tabs and duringsaid molding forming a plurality of conductor receiving openings in saidinsulating materia1 aligned with the openings in said segments, saidopenings formed in said insulating material being substantially the samesize as said openings formed in said segments, said molding materialbeing molded to said anchoring tabs whereby an annular insulator isformed which is connected to said segments and which has openingsaligned with the openings in said segments,

md removing said connecting portions to form insuated commu torsegments, aid aligned openings in

1. A method of manufacturing a disk type commutator for a rotor of adynamoelectric machine, the steps comprising, providing a strip ofelectrically conductive material, cutting said material to form aplurality of wedge-shaped commutator segments connected by thinconnecting portions located along one edge of said strip, forming aconductor receiving opening in each commutator segment by cutting andforcing out two adjacent portions of each segment to form a pair ofintegral anchoring tabs extending axially from said segments, foldingsaid strip into a circular configuration with the edges of said segmentsspaced from each other and with said one edge of said strip located atthe outer periphery, molding a quantity of insulating material to theside of said folded strip having said integral anchoring tabs and duringsaid molding forming a plurality of conductor receiving openings in saidinsulating material aligned with the openings in said segments, saidopenings formed in said insulating material being substantially the samesize as said openings formed in said segments, said molding materialbeing molded to said anchoring tabs whereby an annular insulator isformed which is connected to said segments and which has openingsaligned with the openings in said segments, and removing said connectingportions to form insulated commutator segments, said aligned openings insaid segments and annular insulator adapted to receive axially extendingrotor conductors which are electrically connected to said segments.